Sterols of Amphidinium species in the Operculatum Clade: Predominance of cholesterol instead of Δ8(14) sterols previously considered Amphidinium-specific biomarkers

The dinoflagellates Amphidinium carterae and Amphidinium corpulentum have been previously characterized as having Δ⁸⁽¹⁴⁾-nuclear unsaturated 4α-methyl-5α-cholest-8(14)-en-3β-ol (C_28:1) and 4α-methyl-5α-ergosta-8(14),24(28)-dien-3β-ol (amphisterol; C_29:2) as predominant sterols, where they comprise approximately 80% of the total sterol composition. These two sterols have hence been considered as possible major sterol biomarkers for the genus. Here, we have examined the sterols of four recently identified species of Amphidinium (Amphidinium fijiense, Amphidinium magnum, Amphidinium theodori, and Amphidinium tomasii) that are closely related to Amphidinium operculatum as part of what is termed the Operculatum Clade to show that each species has its sterol composition dominated by the common dinoflagellate sterol cholesterol (cholest-5-en-3β-ol; C_27:1), which is found in many other dinoflagellate genera, rather than Δ⁸⁽¹⁴⁾ sterols. While the Δ⁸⁽¹⁴⁾ sterols 4α-methyl-5α-cholest-8(14)-en-3β-ol and 4α,23,24-trimethyl-5α-cholest-8(14),22E-dien-3β-ol (C_30:2) were present as minor sterols along with another common dinoflagellate sterol, 4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol (dinosterol; C_30:1), in some of these four species, amphisterol was not conclusively observed. From a chemotaxonomic perspective, while this does reinforce the genus Amphidinium's ability to produce Δ⁸⁽¹⁴⁾ sterols, albeit here as minor sterols, these results demonstrate that caution should be used when considering Δ⁸⁽¹⁴⁾ sterols, especially amphisterol, as Amphidinium-specific biomarkers within these species where cholesterol is the predominant sterol.     

Amphidiniella sedentaria gen. et sp. nov. (Dinophyceae), a new sand-dwelling dinoflagellate from Japan

A new sand-dwelling dinoflagellate is described from Sesoko Beach, Okinawa Island, subtropical Japan and its micromorphology is studied by means of light and electron microscopy. The cell consists of a small epitheca and a large hypothecs superficially resembling members of the unarmored genus Amphidinium. The cell is dorso-ventrally flattened and possesses a single chloroplast with a large conspicuous pyrenoid. Transmission electron microscopy revealed that the dinoflagellate possesses typical dinoflagellate cellular organization. Scanning electron microscopy demonstrated that the organism is thecate and the thecal plate arrangement is Po, 4′, 1a, 7″, 5c, 4s, 6″′, 2″″. Most of the characteristics suggest gonyaulacalean affinity of the new species. These are the presence of ventral pore, lack of canal plate, direct contact between the sulcal anterior plate and the flagellar pore, possession of six postcingular plates and asymmetrical arrangement of the antapical plates. Affinity to existing families of the order Gonyaulacales has not been determined. Based on the unique cell shape, thecal plate arrangement and the presence of ventral pore, a new genus, Amphidiniella, is established for this organism and the species is named A. sedentaria Horiguchi gen. et sp. nov.     

Establishing a new genus,Chiharadinium gen. nov. (Peridiniales,Dinophyceae) for a tidal pool dinoflagellate formerly known as Scrippsiella hexapraecingula

To determine its accurate taxonomic position, a tidal pool bloom-forming dinoflagellate, Scrippsiella hexapraecingula was re-investigated using light, scanning and transmission electron microscopy together with a phylogenetic analysis based on concatenated ribosomal DNA sequences. The culture strains used in this study were established from intertidal rock pool samples taken from Jogashima, Kanagawa prefecture and Heisaura, Chiba prefecture, Japan and were identified as S. hexapraecingula originally described by Horiguchi and Chihara from a tidal pool in Hachijo Island, Tokyo, Japan in 1983. The thecal plate arrangement was determined as Po, X, 4′, 3a, 6″, 6c, 5s, 5″′, 2″″. The internal structure was investigated for the first time. The organism has typical dinoflagellate cellular organelles such as a dinokaryotic nucleus, mitochondria with tubular cristae, trichocysts and pusule. The chloroplast was single and connected to the central pyrenoid (stalked type). The eyespot found in the sulcus is of the B type with two rows of superficial intraplastidal lipid globules directly overlain by an extraplastidal single layer of crystalline bricks enveloped by a common membrane. The apical pore is plugged by a double-layered stub-like structure. Stalk building material for attachment covered the apical pore. Phylogenetic analysis indicated that S. hexapraecingula was most closely related to a freshwater dinoflagellate, Peridiniopsis borgei, the type species of the genus Peridiniopsis. However, clear differences exist between these two organisms, including their thecal plate arrangement, habitat and habit. As a result, a new genus, Chiharadinium Dawut & T. Horiguchi gen. nov. has been proposed rather than attempting to accommodate S. hexapraecingula in the genus Peridiniopsis. The new combination, Chiharadinium hexapraecingulum (T. Horiguchi & Chihara) Dawut & T. Horiguchi comb. nov. has been proposed.     

HOT WATER EXTRACTABLE PHOSPHORUS—AN INDICATOR OF NUTRITIONAL STATUS OF PERIDINIUM CINCTUM (DINOPHYCEAE) FROM LAKE KINNERET (ISRAEL)?1

The intracellular levels of hot water extractable and total phosphorus were determined in the dinoflagellate Peridinium cinctum. f. westii (Lemm.) Lef. for natural samples from the bloom in Lake Kinneret and from laboratory cultures. Amounts of phosphorus (P) in the hot water fraction, relative to total cellular phosphorus, were similar in lake Peridinium and in cells grown in high ambient orthophosphate (P_i) media (3–6 mg P · l^?1). The absolute amounts of hot water extractable P in natural cell and those cultured at lower P_i concentrations (0.02–0.05 mg P · 1^?1) were similar, although average P_i in lake water were 4 μg · l^?1. Under most growth conditions the hot water extract contained approximately equal amounts of molybdate reactive phosphorus (MRP) and non-MRP. Short chain (6–9 units) polyphosphates (mol wt 630–950) probably constituted the bulk of the non-MRP pool, which was hydrolysable by alkaline phosphatase and may serve as a precursor for a more permanent P store. Intracellular P levels and distribution were not directly dependent on external P_i concentrations but may be determined by the N:P atomic ratio or overall external ionic milieu. Peridinium grown in low ambient P_i released significant amounts of non-MRP compounds. In Lake Kinneret, for at least most of the bloom period, Peridinium does not appear to be limited by P supply.     

九龙江西陂库区沉积物甲藻孢囊的分布

孢囊在甲藻的生活史中发挥重要作用,福建省九龙江从2009年起,暴发多次拟多甲藻水华事件。采用显微镜观察和单细胞PCR技术,对九龙江西陂库区2012—2013年不同月份沉积物中的甲藻孢囊进行种属判定,并对甲藻孢囊的分布及其影响因素进行分析。结果表明,西陂库区沉积物中的甲藻孢囊主要为拟多甲藻属,约占80%,其次为裸甲藻属,发现了2009年水华的优势种佩式拟多甲藻(Peridiniopsis penardii)孢囊。库区沉积物中甲藻孢囊的丰度在(13.7±1.2)—(105.2±8.3)个/g干重之间。多元相关分析结果显示甲藻孢囊的丰度与含水率呈现显著正相关性(P0.05),反映了甲藻孢囊沿水流方向逐渐积累。本研究结果填补了国内水库甲藻孢囊鉴定和萌发的研究空白,为九龙江甲藻水华的防治提供科学参考。     

Novel renin inhibitors containing derivatives of N‐alkylleucyl‐β‐hydroxy‐γ‐amino acids

In search for new drugs lowering arterial blood pressure, which could be applied in anti‐hypertensive therapy, research concerning agents blocking of renin‐angiotensin‐aldosteron system has been conducted. Despite many years of research conducted at many research centers around the world, aliskiren is the only one renin inhibitor, which is used up to now. Four novel potential renin inhibitors, having structure based on the peptide fragment 8–13 of human angiotensinogen, a natural substrate for renin, were designed and synthesized. All these inhibitors contain unnatural moieties that are derivatives of N‐methylleucyl‐β‐hydroxy‐γ‐amino acids at the P₂‐P₁' position: 4‐[N‐(N‐methylleucyl)‐amino]‐3‐hydroxy‐7‐(3‐nitroguanidino)‐heptanoic acid (AHGHA), 4‐[N‐(N‐methylleucyl)‐amino]‐3‐hydroxy‐5‐phenyl‐pentanoic acid (AHPPA) or 4‐[N‐(N‐methylleucyl)‐amino]‐8‐benzyloxycarbonylamino‐3‐hydroxyoctanoic acid (AAHOA). The previously listed synthetic β‐hydroxy‐γ‐amino acids constitute pseudodipeptidic units that correspond to the P₁‐P₁' position of the inhibitor molecule. An unnatural amino acid, 4‐methoxyphenylalanin (Phe(4‐OMe)), was introduced at the P₃ position of the obtained compounds. Three of these compounds contain isoamylamide of 6‐aminohexanoic acid (ε‐Ahx‐Iaa) at the P₂'‐P₃' position. The proposed modifications of the selected human angiotensinogen fragment are intended to increase bioactivity, bioavailability, and stability of the inhibitor molecule in body fluids and tissues. The inhibitor Boc‐Phe(4‐OMe)‐MeLeu‐AHGHA‐OEt was obtained in the form of an ethyl ester. The hydrophobicity coefficient, expressed as log P varied between 3.95 and 8.17. In vitro renin inhibitory activity of all obtained compounds was contained within the range 10^?6‐10^?9 M. The compound Boc‐Phe(4‐OMe)‐MeLeu‐AHPPA‐Ahx‐Iaa proved to be the most active (IC₅₀ = 1.05 × 10^?9 M). The compounds Boc‐Phe(4‐OMe)‐MeLeu‐AHGHA‐Ahx‐Iaa and Boc‐Phe(4‐OMe)‐MeLeu‐AHPPA‐Ahx‐Iaa are resistant to chymotrypsin. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.     

FURTHER SEM STUDY OF MARINE DINOFLAGELLATES: THE GENUS OSTREOPSIS (DINOPHYCEAE)1

This paper presents a comprehensive examination of the taxonomy of the genus Ostreopsis Schmidt. The morphology of six species of marine dinoflagellates, Ostreopsis siamensis Schmidt 1902. Ostreopsis lenticularis Fukuyo 1981, Ostreopsis ovata Fukuyo 1981, Ostreopsis heptagona Norris, Bomber, et Balech 1985, Ostreopsis mascarenensis Quod 1994, and Ostreopsis labens Faust et Morton 1995 from three geographical regions (Japan, Southwest Indian Ocean, and the Caribbean) and three marine habitats (sand, water column, and macroalgal surfaces) are described from scanning electron micrographs. Differences in the following morphological characteristics differentiated the species: cell shape and size, and ornamentation of the epitheca, cingulum, and hypotheca. The thecal plate formula of the six Ostreopsis species is P_o, 3′, 7″, 6C, 6S?, V_p, R_p, 5′″, 1p, 2″″, with differences in thecal plate size and shape. The cingulum in ventral view has two prominent structures: a ventral plate (V_p) with a ventral pore (V_o) and a ridged plate (R_p) that distinguishes Ostreopsis species from any other dinoflagellate taxa. This paper also includes ecological and toxicity information regarding the six Ostreopsis species.     

Ricerche Sul Fitoplancton del Mare Ligure

Riassunto

Viene completato l'elenco sistematico dei Ceratium viventi nelle acque di Sanremo, descrivendone una nuova specie: Ceratium Brunellii Rampi n. sp., e se ne stabilisce in linca di massima il comportamento fenologico.

Il raffronto del quadro feno-biologico dei Cerazi di Sanremo con quello di altre località mediterranee, sembra indicare che la distribuzione superficiale e la fenologia di questi microplanctonobi, è sensibilmente identica per tutto il bacino mediterraneo e che il gruppo afanotermo delle acque di Sanremo è ad apparizione precoce nei confronti di altre località mediterrance     

Light and scanning microscopy of two benthic species of Amphidiniopsis (Dinophyceae), Amphidiniopsis hexagona sp. nov. and Amphidiniopsis swedmarkii from Japan

Two species of the genus Amphidiniopsis, a marine armoured, sand‐dwelling dinoflagellate, Amphidiniopsis hexagona Yoshimatsu, Toriumi et Dodge sp. nov. and Amphidiniopsis swedmarkii (Balech) Dodge were collected from Japanese sandy beaches, and their morphologic features were observed by light microscopy and scanning electron microscopy. Amphidiniopsis hexagona was hexagonal in ventral view and measured 44–59 urn in length and 40–53 urn in width. The plate formula is P_o, 4′, 2a, 7″, 3c, 4s (+ 2 accessory), 5″″, 2″″. This plate arrangement of A. hexagona is essentially the same as those of Amphidiniopsis hirusta and A. swedmarkii, but this new species can be readily distinguished from the latter two species by the following characters: (i) the cell shape; (ii) the presence of an antapical spine; and (iii) the surface ornamentation of thecal plates.     

PIGMENTS,FATTY ACIDS,AND STEROLS OF THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM1

Cultures and field samples of the toxic dinoflagellate Gymnodinium catenatum Graham from Tasmania, Australia, were analyzed for pigment, fatty acid, and sterol composition. Gymnodinium catenatum contained the characteristic pigments of photosynthetic dinoflagellates, including chlorophyll a, chlorophyll c₂, and the carotenoids peridinin, dinoxanthin, diadinoxanthin, diatoxanthin, and β,β-carotene. In midlogarithmic and early stationary phase cultures, the chlorophyll a content ranged 50–72 pg · cell^?1, total lipids 956–2084 pg · cell^?1, total fatty acids 426–804 pg · cell^?1, and total sterols 8–20 pg · cell^?1. The major fatty acids (in order of decreasing abundance) were 16:0, 22:6(n-3), and 20:5(n-3) (collectively 65–70% of the total fatty acids), followed by 16:1(n-7), 18:2(n-6), and 14:0. This distribution is characteristic of most dinoflagellates, except for the low abundance (<3%) of the fatty acid 18:5(n-3), considered by some authors to be a marker for dinoflagellates. The three major sterols were 4α-methyl-5α-cholest-7-en-3β-ol, 4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol (the dinoflagellate sterol, dinosterol), and 4α,23,24-trimethyl-5α-cholest-7-en-3β-ol. These three sterols comprised about 75% of the total sterols in both logarithmic and early stationary phase cultures, and they were also found in high proportions (22–25%) in natural dinoflagellate bloom samples. 4-Desmethyl sterols, which are common in most microalgae, were only present in trace amounts in G. catenatum. The chemotaxonomic affinities of G. catenatum and the potential for using specific signature lipids for monitoring toxic dinoflagellate blooms are discussed.     

Mono- and digalactosyldiacylglycerol composition of dinoflagellates. V. The galactolipid profile of Alexandrium tamarense (Dinophyceae) during the course of infection by the parasitic syndinian dinoflagellate Amoebophrya sp.

Amoebophrya is a parasitic, syndinian dinoflagellate genus that must infect another host dinoflagellate in order to reproduce. Work by Park et al. [Mar. Ecol. Prog. Ser., 227: 281–292 (2002)] has led to the hypothesis that Amoebophrya's development within a host cell nucleus disrupts the flow of genetic information involved in plastidial function. The possibility that genetic disruption by this parasite could lead to alterations in plastidial lipid composition during the course of an infection has not yet been elucidated. Our primary objective in this lipidomic study was to examine the chloroplast membrane galactolipid composition of Alexandrium tamarense infected by an Amoebophrya species in order to determine whether infection of A. tamarense causes a phenotypic alteration in the composition of mono- and digalactosyldiacylglycerol (MGDG and DGDG, respectively), two galactolipids that comprise the majority of photosynthetic membranes. Our secondary objective was to determine if non-photosynthetic Amoebophrya sp. either incorporated host cell MGDG and DGDG, and/or itself produced forms of MGDG and DGDG, as has been observed previously in heterotrophic apicomplexan parasites distantly related to Amoebophrya. We found that, despite development of Amoebophrya sp. within the nucleus, the composition of A. tamarense MGDG and DGDG did not change throughout the infection process. The predominant forms of these galactolipids were 18:5/18:4 (sn???1/sn?2) and 20:5/18:4 DGDG, which were present at similar abundances in both an uninfected host and a host late in the infection process just prior to release of Amoebophrya sp. dinospores. Amoebophrya sp. did not possess appreciable amounts of any forms of MGDG and DGDG.     

Crystallization,characterization, and preliminary crystallographic studies of mitochondrial carbamoyl phosphate synthetase I of Rana catesbeiana

Carbamoyl phosphate synthetase I (ammonia; E C 6.3.4.16) was purified from the liver of Rana catesbeiana (bullfrog). Crystals of the protein have been obtained at 22°C by the hanging drop vapor diffusion technique, with polyethylene glycol as precipitant. Tetragonal crystals of about 0.3 × 0.3 × 0.7 mm diffract at room temperature to at least 3.5 Å using a conventional source and are stable to X-radiation for about 12 h. Therefore, these crystals are suitablefor high resolution studies. The space group is P4₁2₁2 (or its enantiomorph P4₃2₁2), with unit cell dimensions a = b = 291.6 Å and c = 189.4 Å. Density packing considerations areconsistent with the presence of 4-6 monomers (M_r of the monomer, 160,000) in the asymmetric unit. Amino-terminal sequence of the enzyme and of a chymotryptic fragment of 73.7 kDa containing the COOH-terminus has been obtained. The extensive sequence identity with rat and human carbamoyl phosphate synthetase I indicates the relevance for mammals of structural data obtained with the frog enzyme. © 1995 Wiley-Liss, Inc.     

Abstracts of Papers read at the Winter Meeting at Queen Elizabeth College,London

A new heterotrophic armoured dinoflagellate is described from sand habitats in eastern Australia. Cabra matta gen. nov., sp. nov., lacks plastids and an eyespot. The thecal plate formula is Po 4′ 4” ‘x’ 3c ?s 5′′’ 1′′”. Its plate pattern differs from all currently described dinoflagellate genera, but is most similar to the genus Roscoffia. Cabra matta shows some similarity to species currently placed in the family Podolampaceae, however its evolutionary affinities and hence its position within the dinoflagellate systematic hierarchy remain unresolved.     

THE PHYSIOLOGICAL ECOLOGY OF A FRESHWATER DINOFLAGELLATE BLOOM POPULATION: VERTICAL MIGRATION,NITROGEN LIMITATION,AND NUTRIENT UPTAKE KINETICS1,2

The motile freshwater dinoflagellate Gymnodinium bogoriense Klebs., which forms dense blooms in Jezre'el Valley water reservoirs (Israel) appears to be physiologically suited to exploit stratified environments, where it outcompetes all other phytoplankton types. The dense summer blooms (“red tides”) were found to be nitrogen-limited. The algae's competitive advantage, however, cannot result from superior uptake capabilities: its K_s (μmol NH₄·L^?1) for NH₄ was higher and its V_maxμmol NH₄·mg chlorophyll a^?1·h^?1) was lower than other phytoplankton types commonly occurring in the region. The competitive advantage of G. bogoriense probably stems from other physiological capabilities: dark ammonia and phosphorus assimilation and the ability to undertake diel vertical migration cycles between the upper photic water layers during the day and nutrient-rich deeper layers at night. These findings confirm the vertical nutrient retrieval hypothesis in migrating phytoplankton.